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PubMed2004

A comparison between 90 degrees and 180 degrees selective laser trabeculoplasty.

PURPOSE: To compare two regimens of SLT, ie, SLT with 25 laser spots on 90 degrees of trabecular meshwork and SLT with 50 laser spots on 180 degrees of trabecular meshwork in patients with open-angle glaucoma. PATIENTS AND METHODS: In a prospective clinical study, the authors compared pressure-lowering effect of SLT in 2 groups of patients; 1 group (32 patients) received SLT with 25 laser spots on 90 degrees of trabecular meshwork, the other group (32 patients) SLT with 50 laser spots on 180 degrees of trabecular meshwork. RESULT: There was no difference in the pressure reduction between these two treatment regimens. Moreover, the pressure reduction was not influenced by previous ALT treatments. The pigmentation in the trabecular meshwork is related to a delayed effect on the pressure lowering after SLT. CONCLUSION: SLT with 25 laser spots on 90 degrees of trabecular meshwork has a similar pressure-lowering effect to SLT with 50 laser spots on 180 degrees of trabecular meshwork. The new treatment regimen with less laser spots could increase the repeatability of SLT and reduce potential tissue damage in the trabecular meshwork.

Aged↗
PubMed1984

[Argon laser trabeculoplasty. Initial results of a prospective study].

This paper presents the results of a prospective study on argon laser trabeculoplasty with clinical application in 166 cases up to now. So far, patients have been followed up for between 2 and 12 months. Low-intensity coagulation was performed over 360 degrees of the trabecular meshwork. The coagulation site within the trabecular meshwork was chosen according to the outflow facility as measured by tonography. In eyes with high outflow facility (C greater than 0.08) the unpigmented, so-called nonfunctioning trabecular meshwork was coagulated. Where the outflow facility was lower (C less than 0.03), a pigmented area of the trabecular meshwork was aimed at. Where the facility was intermediate (0.08 greater than C greater than 0.03) the border area between pigmented and nonpigmented meshwork was coagulated. Three groups of patients were treated: (1) older patients with insufficient compliance; (2) patients whose intraocular pressure (IOP) was poorly controlled by drugs and was under 35 mm Hg; (3) patients suffering from glaucoma in aphakia or status post trabeculectomy and poor control of IOP. Applying these criteria , IOP was controlled in 26.8% without additional drugs and in 68% in combination with local medication after 6 weeks. Very few complications were seen (8 cases), and they did not lead to deterioration or loss of vision. In the light of theoretical considerations and initial histopathologic findings in human eyes, the authors assume that low-intensity coagulation causes a denaturation and shrinkage of the trabecular collagen, leading to stretching of the surrounding trabecular structures.(ABSTRACT TRUNCATED AT 250 WORDS)

Humans↗
PubMed1976

[Clinical and morphological studies in a case of congenital glaucoma combined with an ocular-dental-digital dysplasia (author's transl)].

Clinical and morphological studies were undertaken to characterize a case of congenital glaucoma combined with an ocular-dental-digital dysplasia in a two year old patient. Light and electromicroscopic investigations of a surgically removed trabecular specimen were carried out. A trabeculotomy had been performed at this exact site 10 months prior to removal. The existence of a canal of Schlemm was demonstrated. The regular trabecular meshwork and trabecular region was replaced by fairly dense scar tissue, containing rudimentary intertrabecular spaces. Proliferating corneal endothelial cells covered the wound area up to the uveal part of the trabecular region. The morphological findings correlated well with the clinical observation of continued raised intraocular pressure despite trabeculotomy. It is concluded that, contrary to the situation in adult onset glaucoma, the strong proliferative tendency of juvenile tissue has a marked influence on the postoperative efficacy of the trabeculotomy.

Child, Preschool↗
PubMed2006

Retinal nerve fiber layer analysis in the diagnosis of glaucoma.

PURPOSE OF REVIEW: The detection of optic disc and retinal nerve fiber layer damage and change is the cornerstone of glaucoma management. Assessment of the retinal nerve fiber layer for localized and diffuse damage has been traditionally based on clinical examination, with documentation of change primarily qualitative. With the latest improvements in optical imaging instruments, objective and quantitative measurements of the retinal nerve fiber layer are now possible. This review summarizes the results from recent cross-sectional studies evaluating the discriminating ability of automated retinal nerve fiber layer measurements to detect glaucoma, and from longitudinal studies assessing the ability to predict and monitor glaucomatous changes. RECENT FINDINGS: Numerous cross-sectional studies have documented good diagnostic accuracy of a scanning laser polarimeter (GDx VCC), the optical coherence tomograph (Stratus), and the Heidelberg Retina Tomograph retinal nerve fiber layer measurements for differentiating between healthy and glaucoma eyes. There are only limited data available on the ability of these retinal nerve fiber layer measurements to document change over time. SUMMARY: It is essential that the clinician understand the specific strengths and weaknesses of each technique so that only good quality retinal nerve fiber layer information will be used in conjunction with careful clinical examination and visual function testing for glaucoma management decisions. Longitudinal studies are needed to evaluate the ability of these instruments to document retinal nerve fiber layer change over time.

Diagnostic Imaging↗
PubMed1989

Morphologic features of the aqueous humor drainage pathways in horses.

The iridocorneal angle of the horse was anteriorly lined by a pectinate ligament, consisting of several layers of vertically oriented collagenous beams, that were interrupted by a network of extracellular spaces. The anterior chamber angle consisted mostly of a large uveal trabecular meshwork that was composed of widely-spaced, thick trabeculae. These trabeculae were attached in part posteriorly to extensions of the ciliary body musculature and anteriorly inserted into the prominent pectinate ligament. The corneoscleral trabecular meshwork was shaped hemiobovately and formed the external boundary of the iridocorneal angle. The extracellular spaces were smaller and more evenly spaced than those in the uveal trabecular meshwork. Uveal and corneoscleral trabecular meshwork beams were mostly composed of cores of collagen and elastin surrounded by several layers of basement membrane-like material and, in turn, were entirely enveloped by trabecular cells. An anterior narrow zone of broad corneoscleral trabeculae was composed of elastin-collagen cores surrounded by circular bundles of long-spacing collagen. The angular aqueous plexus was extensive, forming much of the external border of the outer corneoscleral trabecular meshwork. A dense zone was associated with the angular aqueous plexus, completely encompassing these aqueous outflow vessels. Posteriorly, the iridocorneal angle was confluent with a well-defined band of trabeculae that was situated between the ciliary body musculature and subjacent sclera and extended posteriorly to the anterior-most region of the choroid where these trabeculae tapered and ended. This region is referred to as the supraciliary trabecular meshwork and indicates a potentially extensive route for outflow of aqueous humor in the equine eye.

Animals↗
PubMed1993

Serum proteins and aqueous outflow resistance in bovine eyes.

PURPOSE: Recent evidence shows that much of the protein in the anterior chamber aqueous humor enters diffusively through the root of the iris. The proximity of the protein entry point to the trabecular meshwork suggests that the protein content of the aqueous humor in the trabecular meshwork might be much higher than previously suggested. The authors were interested in investigating the possible hydrodynamic implications of these proteins. METHODS: Bovine eyes were perfused with concentrations of bovine serum in buffer ranging from 0% to 15% to determine the effect on outflow resistance. Immunohistochemical methods were used on these eyes and unperfused eyes to determine the distribution of albumin in the anterior segment. RESULTS: Preliminary perfusion studies suggested that increasing the concentration of serum in buffer from 0% to 15% decreased the rate of "wash-out" in bovine eyes, with a 15% solution essentially eliminating the wash-out phenomenon. Perfusion of a series of bovine eyes with a total of 5 ml of 15% serum in buffer showed a "wash-out" rate of 0.0498 +/- 0.0428 ([microliters/min/mm Hg]/[ml perfusate]), whereas control eyes perfused with buffer washed-out at a rate of 0.1677 +/- 0.0271 (P < 0.05); a second series of eyes perfused with a total of 10 ml of 15% serum washed-out at a rate of 0.0533 +/- 0.0294, whereas control eyes had a rate of 0.1813 +/- 0.0342 (P < 0.02). Immunohistochemical investigations showed significant quantities of albumin in the outflow pathway of unperfused eyes, whereas perfusion with buffer eliminated this protein; perfusion with 10% to 15% serum in buffer maintained the level of albumin in the outflow pathway similar to that found in unperfused eyes. Use of cuprolinic blue in a critical electrolyte concentration confirmed previous findings that sulfated proteoglycans are not eliminated from the trabecular meshwork during wash-out. CONCLUSIONS: Wash-out in nonhuman species may result from progressive depletion of an anterior segment depot of plasma-derived proteins entering the trabecular meshwork. Modeling studies confirm that plasma-derived proteins in the aqueous humor of the trabecular meshwork can generate a significant fraction of aqueous outflow resistance. The lack of wash-out in human eyes suggests that this system may maintain flow resistance in a fashion fundamentally different from other species.

Animals↗
PubMed1991

Ultrastructural alterations in the aqueous outflow pathway of adult buphthalmic rabbits.

The aqueous outflow pathway of adult rabbit eyes with congenital glaucoma (buphthalmos) was examined by light microscopy and by scanning and transmission electron microscopy. The morphology of the buphthalmic rabbit aqueous outflow pathway was markedly abnormal when examined at 6 months, 1 yr, and 2 yr displaying apparent loss and/or compression of the iris pillars, dilation of the intertrabecular spaces, loss of endothelial cell-to-cell association and disorganization of trabecular lamellae, and posterior displacement of the aqueous plexus. In addition, the trabecular meshwork lamellae were observed only adjacent to the sclera and the inner portion of the trabecular meshwork was limited to swirls of collagen with scattered cells. These morphological findings suggest that the disease process in the rabbit principally involves an alteration in the differentiation and maintenance of the structural integrity of the trabecular meshwork. The loss of structural support of the buphthalmic trabecular meshwork may be a factor in the wide variation in intraocular pressure and may allow for compression of the trabecular meshwork against the aqueous plexus.

Animals↗
PubMed1985

A morphologic and morphometric analysis of the aqueous outflow system of the developing cat eye.

The cellular and tissue changes accompanying the development and growth of the aqueous outflow system of the cat were investigated by quantitative light microscopy and by scanning and transmission electron microscopy. As in primates, the trabecular beams and sheets of the cat aqueous outflow system developed by reorganization of cells and extracellular matrix within the tissue filling the anterior chamber angle recess. Enlargement and coalescence of intercellular spaces gave rise to intertrabecular channels. From 3 to 9 days after birth, communications were established between the anterior chamber and intertrabecular spaces by perforation and resorption of tissue which initially covered the angle apex and appeared to be a peripheral extension of Descement's membrane and the corneal endothelium. Macrophage-like cells could be involved in this process. A rapid increase in the volume of the intertrabecular spaces and in the number of trabecular cells coincided with the opening of the trabecular meshwork to the anterior chamber. The trabecular meshwork grew 150-fold in volume from birth to adulthood, mainly as a result of a similar-fold expansion of its connective tissue components. The volume of the intertrabecular spaces increased 24-fold and trabecular cell number increased 14-fold during this same period. The disproportionate increase in volume of the various components of the trabecular meshwork was responsible for the decreased cell density and rarefaction displayed by this tissue as development progressed. Development of the aqueous outflow system of the cat is thus a complex, but highly co-ordinated, process, that depends on continued proliferation of cells and extracellular matrix, a progressive ordering of these components, and selective atrophy and removal of specific tissue components.

Aging↗
PubMed2004

Studies on the mechanism of action of timolol and on the effects of suppression and redirection of aqueous flow on outflow facility.

Long-term use of drugs that suppress aqueous humor formation, such as timolol and dorzolamide, or that redirect aqueous humor outflow from the trabecular meshwork, such as prostaglandin F2alpha analogues, could cause underperfusion of the trabecular meshwork and a secondary decrease in outflow facility. We investigated the mechanism of suppression of aqueous humor formation by timolol in monkey eyes by measuring aqueous humor ascorbate levels. We also determined whether suppression of aqueous humor formation with and without redirection of aqueous humor away from the trabecular meshwork could lead to a subsequent reduction in outflow facility, and whether this reduction was correlated with increased fibronectin levels in anterior chamber aqueous humor. In cynomolgus monkeys, unilateral dose/aqueous humor formation response curves were generated for timolol, dorzolamide, and a combination of timolol + dorzolamide. Aqueous humor formation and/or outflow facility were measured in both eyes after approximately four days, four weeks and seven weeks of twice daily treatment with 3.5 microg timolol + 1.0 mg dorzolamide to one eye and 30% DMSO to the other. In some monkeys, 5 microg prostaglandin F2alpha-isopropyl ester (PG) was added to timolol + dorzolamide for 4-week treatments. Intraocular pressure and corneal endothelial transfer coefficients (k(a)) were also measured at four weeks. Aqueous humor fibronectin levels were determined in four monkeys after approximately 9.5 weeks of timolol + dorzolamide treatment. Aqueous humor formation, intraocular pressure, and aqueous humor ascorbate levels were also determined in rhesus monkeys at baseline and after a single unilateral topical administration of 25 microg timolol. Compared to baseline for the same eye, aqueous humor formation was significantly decreased in treated eyes at all doses of timolol and at 1.8 and 4 mg dorzolamide. Compared to the opposite control eye, aqueous humor formation was lower in treated eyes after 3.5 and 5 microg timolol and after all doses of dorzolamide. Aqueous humor formation after treatment with 3.5 microg timolol + 1.0 mg dorzolamide was decreased in treated vs. control eyes, after four days and was suppressed in both treated and control eyes after four weeks of treatment, but not when PG was added. There was no difference in k(a) values with or without the addition of PG. Intraocular pressure was significantly lower in both treated and control eyes vs. baseline after approximately 6.5 weeks treatment with timolol + dorzolamide when taken 2 hr after the last dose and after approximately 3.5 weeks treatment with timolol + dorzolamide + PG when measured 6 hr after the last dose. Outflow facility after treatment with timolol + dorzolamide was unchanged after four days, tended to be lower in the treated vs. control eyes after four and seven weeks, and was significantly lower in treated vs. control eyes after four weeks treatment with timolol + dorzolamide + PG (0.352 +/- 0.052 vs. 0.515 +/- 0.096 microl min(-1) mmHg(-1), p < or = 0.02). Both treated vs. control eye aqueous humor fibronectin levels were below the level of detection for our assay (0.01 microg ml(-1)). The 25 microg timolol dose decreased ipsilateral, but not contralateral intraocular pressure (12.6 +/- 1.7 vs. 15.2 +/- 0.9; p < 0.05) and aqueous humor formation (1.40 +/- 0.08 vs. 2.03 +/- 0.09 microg ml(-1), p < or = 0.01). There was no difference in anterior chamber ascorbate levels in treated vs. control eyes or compared to their respective baselines. Our findings indicate that timolol affects neither ciliary epithelial transport of ascorbate nor aqueous fibronectin levels. Our data also indicate that decreasing aqueous humor formation over a period of time can lead to reduction in outflow facility, particularly when combined with therapy that redirects aqueous from the trabecular meshwork. Future intraocular pressure-lowering therapies for glaucoma may better be directed at enhancing flow through the trabecular pathway as opposed to decreasing aqueous humor formation or rerouting aqueous humor away from the trabecular meshwork.

Adrenergic beta-Antagonists↗
PubMed1999

Ultrasound biomicroscopical study of the irido-corneal angle in dominant juvenile open-angle glaucoma, in POAG, and in normal eyes.

PURPOSE: To compare various parameters of the chamber angle in a pedigree with dominant goniodysgenesis and juvenile open-angle glaucoma linked to chromosome 1q, GLC1A, with those in patients with adult-onset primary open-angle glaucoma, and in normal eyes. METHODS: Ultrasound biomicroscopy was performed on 10 eyes with dominant goniodysgenesis and juvenile open-angle glaucoma, on 12 eyes with adult-onset primary open-angle glaucoma, and 24 normal eyes. Eight parameters were measured. RESULTS: The anterior chamber angle, angle opening distance 500 microm from the scleral spur, trabecular meshwork--iris distance, and trabecular meshwork--iris pigment epithelium distance were statistically significantly higher in the group with juvenile glaucoma. CONCLUSION: The wider chamber angle in dominant juvenile open-angle glaucoma could suggest a more complex anomaly with involvement of cornea and iris in addition to goniodysgenesis. The presence of goniodysgenesis in the dominant juvenile open-angle glaucoma patients could not be detected by ultrasound biomicroscopy, however.

Adult↗
PubMed1993

Immunohistochemical monitoring of the effect of a synthetic fibronectin-like peptide (Arg-Gly-Asp) on the age-related changes in the isolated human corneoscleral tissue of glaucomatous eyes.

Fibronectin, an adhesion glycoprotein has been detected and localized in samples of the trabecular meshwork from eight normotensive and 30 glaucomatous human eyes of various ages by means of the indirect immunoperoxidase staining technique. Fibronectin concentration in the trabecular meshwork tissue was evaluated by morphometric analysis. Deposits of the adhesion glycoprotein fibronectin were shown to be spread in the ocular drainage outflow system from patients along with progressive primary open-angle glaucoma (POAG). The fibronectin level quantitatively evaluated in serial cross-sections of trabecular meshwork, appeared to be increased during ageing and more rapidly in the event of POAG development. The active amino acid sequence in fibronectin is an arginine-glycine-aspartic acid tripeptide (Arg-Gly-Asp) and it was shown that the synthetic Arg-Gly-Asp peptide specifically inhibited the adhesive function of fibronectin in trabecular meshwork samples when incubated for 30 min at a concentration of 1-2 mg/ml. The peptide concentration necessary for a 50% decrease of the maximal fibronectin level in the trabecular meshwork specimen derived from patients with moderately advanced POAG stage, was about 1 mg/ml. Immunohistochemical staining exhibited a fainter fibronectin staining in trabecular tissues including the external trabecular layers and subendothelial region of Schlemm's canal, in samples incubated with the synthetic peptide compared with the same tissue explants before peptide treatment. It may be concluded that the adhesion control system is likely to play an important role in development and maintenance of tissue architecture and specialization of the normal human trabecular meshwork.

Aged↗
PubMed2006

[Trabeculoplasty with two different lasers in cats, monkeys and humans: a scanning electron microscopy study].

PURPOSE: To study the structural changes induced by trabeculoplasty with two different lasers (Ti-Sph and argon) and observe the differences between four trabecular meshwork models. MATERIALS AND METHODS: Four different trabecular meshwork (TM) models were used from cats, monkeys, and humans. This study was performed on fresh cadaver eyes ("ex vivo") except for the cat in which this study was performed "in vivo". The morphology of the trabecular meshwork was observed by scanning electron microscope (40/100X) after being treated with argon (0.1s/pulse, 600 to 1,000 mW, 50 microm spot size) and Ti-Sph (7 microsg/pulse, 25 to 110 mJ,175 microm of spot size). The study on cats allowed assessment of the induced effect after 24 hours, and 4 weeks after the treatment on the TM. Typical clinical trabeculoplasty parameters were used for both lasers during this study. RESULTS: The models used in this study were found to be adequate for trabeculoplasty. They exhibited a deep anterior chamber and an accessible TM. The argon laser induced significant changes in the TM in all models studied. The cat model demonstrated TM repair response one month after treatment. For Ti-Sph, high levels of energy (>100 mJ) were required to induce significant structural changes in the TM. CONCLUSION: The IOP reduction effect by argon trabeculoplasty (600/1,000 mW) induced structural shrinkage of the collagen in the TM via thermal effects. The Ti-Sph laser works through non-structural mechanisms. At clinical levels (lower than 80 mJ), Ti-Sph does not show evidence of TM changes.

Animals↗
PubMed1998

Laminin heterogeneity around Schlemm's canal in normal humans and glaucoma patients.

BACKGROUND: The laminins play an important role in cell attachment to the extracellular matrix. This study was undertaken in order to investigate and to compare the presence of several laminin chains and isoforms in normal and glaucomatous trabecular meshwork. METHODS: Fresh-frozen trabeculectomy specimens from glaucoma patients and trabecular meshwork from human donor eyes were included for immunohistochemistry. We used antibodies against laminin 1 (EHS-laminin/alpha1beta1gamma1), laminin 2 (merosin/alpha2,beta1gamma1), the subunits of alpha2 (M laminin), beta1 B1laminin), gamma1 (beta2laminin) and beta2 (s laminin) and gamma2 and the associated glycoprotein nidogen. RESULTS: For laminin 1, laminin 2, the subunits alpha2;, beta1, beta2, gamma1 and nidogen, the immunoreactivity of the juxtacanalicular zone underneath the inner wall of Schlemm's canal was always stronger than of the uveal and corneoscleral trabecular meshwork. Staining for laminin chain gamma2 could not be demonstrated in the outflow structures. Pattern and intensity of labelling for the laminins were not different between normal and glaucomatous eyes. DISCUSSION: Heterogeneity of the laminins suggests structural complexity of the juxtacanalicular region. However, the presence of laminin around Schlemm's canal seems to be unaffected by glaucoma and by age. This might indicate maintenance of basement membrane stability in the trabecular meshwork for life.

Adult↗
PubMed1999

Immediate intraocular pressure response to selective laser trabeculoplasty.

BACKGROUND/AIMS: Selective laser trabeculoplasty targets the pigmented trabecular meshwork cells without damage to the trabecular meshwork architecture in vitro. A study was conducted in vivo of eight eyes with uncontrolled open angle glaucoma to ascertain the immediate intraocular response to selective laser trabeculoplasty. METHODS: The trabecular meshwork of each eye was treated 360 degrees with a frequency doubled Q-switched Nd:YAG laser. Intraocular pressure was measured 1, 2, 24 hours and 1, 4, 6 weeks after treatment. RESULTS: The average preoperative intraocular pressure was 26.6 (SD 7) mm Hg (range 18-37). Two hours and 6 weeks respectively after selective trabeculoplasty intraocular pressure was reduced in all the eyes treated with an average fall of 10.6 (5.2) mm Hg or 39.9%. A pressure spike of 10 mm Hg verified in one eye 1 hour after treatment. CONCLUSIONS: Selective laser trabeculoplasty decreased intraocular pressure by an amount similar to that achieved with standard trabeculoplasty. Additional study is needed to determine whether the beneficial effect is sustained over a longer period of follow up.

Aged↗
PubMed1986

Experimental obstruction to aqueous outflow by pigment particles in living monkeys.

Pigment particles (1 X 10(6)/microliters) isolated from the iris and ciliary body of enucleated cynomolgus monkey eyes were infused into the anterior chamber of seven living cynomolgus monkeys and aqueous humor outflow facility determined by the two-step constant-pressure perfusion technique. Outflow facility acutely decreased 64% in the experimental pigment perfused eyes compared to a 76% increase in the sham-manipulated fellow eyes (P less than 0.001). However, when next measured 1 wk later, facility in the pigment perfused eyes had returned to baseline levels. Repetitive pigment perfusions similarly failed to produce any long-term abnormality in outflow facility. Gonioscopically, a well-defined band of pigment was observed in the trabecular meshwork, which decreased in density with time. Scanning and transmission electron microscopy documented pigment particle phagocytosis by trabecular endothelial cells and macrophages. Forty-two and 105 days after pigment infusion the trabecular meshwork was normal morphologically, and, despite an observed decrease in trabecular pigmentation, morphometry failed to reveal a decrease in trabecular meshwork cellularity in experimental compared to control eyes. These results suggest that factors other than, or in addition to, pigment particle accumulation in the trabecular meshwork must be involved in the mechanism of human pigmentary glaucoma.

Animals↗
PubMed2002

Individual factors influencing trabecular morphology in glaucoma patients undergoing filtration surgery.

PURPOSE: Epidemiologic studies have shown that various lifestyle characteristics are statistically associated with the chronic open-angle glaucomas. This study was designed to investigate the influence of individual factors on the light-microscopic morphology of the trabecular meshwork in open-angle glaucomas. METHODS: Quantitative computer-assisted topographic analysis of the trabecular meshwork was performed in meridional sections of 80 trabeculectomy specimens from patients with primary open-angle (n = 36), exfoliative (n = 30) and pigment-dispersion (n = 14) glaucoma. Measurements included inner wall length of the, central thickness of the trabecular meshwork, and compactness of the Schlemm canal and trabecular meshwork. Morphologic data were correlated with individual patient data including age, duration of the disease, maximum intraocular pressure, cup-disc ratio, refraction, height, weight, body mass index, a simple morbidity index, previous surgery, and number of topical antiglaucomatous medications used. RESULTS: Inner wall length of the Schlemm canal was significantly lower in eyes with previous filtering surgery (P = 0.03), but not in eyes with a high number of topical medications (P = 0.17). There was a significant tendency for the inner wall length of the Schlemm canal to be shortened in patients where high maximum intraocular pressure was combined with long-term glaucoma (P = 0.027). Body mass index did not differ significantly between patients with primary open-angle, exfoliative, and pigment-dispersion glaucoma and showed no correlation with the quantitative data of the meshwork. The morbidity index correlated well with body mass index (0.0006) and age (P < 0.0001). CONCLUSION: Contrary to findings of experimental mice studies, we found no indication that glaucoma patients with lower body mass index have a larger lumen of the Schlemm canal than patients with a higher body mass index. Although caution should be used when interpreting data from trabeculectomy studies, there is a certain probability that a history of previous filtering surgery and of a long-term high intraocular pressure will be associated with a shortening of the Schlemm canal.

Adult↗
PubMed1996

Neovascular tissue in the intertrabecular spaces in eyes with neovascular glaucoma.

AIMS/BACKGROUND: To investigate histological changes in the trabecular meshwork in eyes with neovascular glaucoma. METHODS: Light and electron microscopic studies were carried out on the trabecular meshwork of three enucleated eyes with neovascular glaucoma. The presence and distribution of factor VIII in the trabecular meshwork was assessed using the ABC method. RESULTS: Peripheral anterior synechiae covering the trabecular meshwork were detected in two eyes, which would explain the rise in intraocular pressure. In the third the angle was not completely closed by peripheral anterior synechiae. The spaces between the trabecular beams were lined by a single layer of vascular endothelium, and were filled with red blood cells in this patient. Factor VIII was positively stained in the endothelial cells, lining both these spaces and Schlemm's canal. A basal lamina and microfibrils were detected just beneath the newly formed vascular endothelial cells. CONCLUSION: The neovascular tissue found in the trabecular spaces might be one of the factors responsible for intraocular pressure elevation in eyes with neovascular glaucoma.

Adult↗
PubMed1987

Parameters for neodymium-YAG laser trabeculotomy: an in-vitro study.

A Biophysic Médical Nanolas Q-Switched pulsed neodymium-YAG laser has been used to produce lesions in human trabecular meshwork in vitro. Sectors of corneoscleral tissue containing trabecular meshwork were suspended in a waterbath which had had a Trokel gonioscopic contact lens mounted into one side by means of a watertight seal. The laser was used to produce lesions in the trabecular meshwork on either side of each specimen. The energy levels delivered ranged from 0.5 to 7.0 mJ, and convergence angles of 10 degrees and 18 degrees were employed. The energy levels required to produce discrete lesions into the canal of Schlemm without perforating the underlying sclera were 3.0-5.0 mJ at the 10 degrees convergence angle and 4.0-6.0 mJ at the 18 degrees convergence angle setting. It is recommended that such data be determined for each type of laser prior to attempting short-pulsed laser internal trabeculotomy in patients with glaucoma.

Humans↗